Light emitting device

ABSTRACT

light emitting device in which a bonding pad is soldered to a mounting substrate, wherein the bonding pad may be formed in various shapes that can minimize the occurrence of voids during soldering or heat fusion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part of International PatentApplication No. PCT/KR2015/008841, filed on Aug. 24, 2015, and claimspriority from and the benefit of Korean Patent Application No.10-2014-0113470, filed on Aug. 28, 2014, Korean Patent Application No.10-2014-0194260, filed on Dec. 30, 2014, and Korean Patent ApplicationNo. 10-2015-0116740, filed on Aug. 18, 2015, each of which isincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

Exemplary embodiments of the invention relate to a light emittingdevice, and, more particularly, to a light emitting device including abonding pad soldered to a mounting substrate and having a particularstructure capable of minimizing occurrence of voids during soldering.

Discussion of the Background

A high output light emitting device can be obtained by taking intoaccount various design factors such as improvement in luminous efficacy,reduction in package size, and/or reduction in thermal resistance. Aflip-chip type light emitting device is one type of the high outputlight emitting device having such features that is widely used in theart.

Flip-chip bonding means a chip bonding method that utilizes solder bumpsto reduce bonding inductance to 1/10 or less. Since substantially nobonding length may exist in the flip-chip bonding, as compared to aconventional wire bonding, such chip packages may be integrated to ahigher degree.

To achieve the foregoing design objectives, a flip-chip type lightemitting device may be configured to emit light through a substrate inorder to reduce light loss in electrode pads. The flip-chip type lightemitting device may also include a reflective layer on a p-typesemiconductor layer in order to improve extraction efficiency bychanging a course of photons traveling towards a mounting substrate intoan opposite direction. Further, the flip-chip type light emitting devicemay have an improved current spreading efficiency, which enablesapplication of low forward voltage.

In addition, although a high output h emitting device typicallygenerates large amounts of heat upon application of high injectioncurrent, distance from an active layer corresponding to a heatgeneration region to a heat dissipation structure in the light emittingdevice is short, thereby enabling easy heat dissipation and significantreduction in thermal resistance. Accordingly, most high output lightemitting devices such as large light emitting devices are of theflip-chip type design.

Various structures have been used for assisting current spreading in alarge light emitting device that may utilize a flip-chip bonding. Forexample, an active layer interposed between a first conductive typesemiconductor layer and a second conductive type semiconductor layer maybe divided into two or more sections, such that the two or more activelayers share one first conductive semiconductor layer.

In flip-chip bonding, a solder bump is melted by application of a heatthereto to realize electrical connection between a bonding pad of a chipand a mounting substrate, and a process of melting the solder bump maybe referred to as a reflow process.

In the reflow process, a flux is evaporated and may generate bubbles,which in turn are trapped into the molten solder that generates voidsduring solidification of the molten solder. Voids act as a main factorthat weakens heat dissipation and causes a connection failure betweenthe bonding pad of the chip and the mounting substrate, therebydeteriorating reliability of a light emitting device.

Therefore, there is a need in the art to minimize the occurrence ofvoids in order to improve reliability of light emitting devices,particularly high output light emitting devices such as flip-chip typeslight emitting devices.

The above information disclosed in this Background section is only forenhancement of understanding of the context of the inventive concept,and, therefore, may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The invention meets the aforementioned need in light emitting devices byproviding a bonding pad or similar structure, which is soldered or heatfused to a mounting substrate and has a particular structure capable ofminimizing the occurrence of voids during soldering or other heat fusingor connection process.

Exemplary embodiments of the present disclosure may also provide a lightemitting device capable of minimizing occurrence of defects duringsoldering or fusing.

Exemplary embodiments of the invention may further provide a highefficiency light emitting device that generates uniform light over awide area of an active layer through uniform current spreading, therebyimproving luminous efficacy, and a light emitting module including thesame.

Exemplary embodiments of the invention provide a light emitting deviceand a light emitting module that may prevent current crowding at cornersthereof.

Exemplary embodiments of the invention also provide a flip-chip typelight emitting device and a light emitting module that may reduce lossof light generated in an active layer.

More particularly, according to one exemplary embodiment, a lightemitting device includes a first bonding pad configured to be solderedto a mounting substrate, a first electrode electrically connected to thefirst bonding pad via a first connection electrode, a first conductivetype semiconductor layer connected to the first electrode, and a solderball contactable region and a non-conductive region, in which the firstbonding pad includes at least two elongate, opposed regions disposed inthe solder ball contactable region, and the non-conductive region isdisposed between the at least two elongate, opposed regions.

According to one exemplary embodiment, a light emitting device includesa first bonding pad configured to be soldered to a mounting substrate, afirst electrode electrically connected to the first bonding pad via afirst connection electrode, and a first conductive type semiconductorlayer connected to the first electrode, in which the first bonding padis disposed in a portion of a solder ball contactable region, and anon-conductive pattern is disposed in the remaining portion of thesolder ball contactable region, through which by-products generatedduring soldering escape.

Other features may be used in particular exemplary embodiments of theinvention. For example, the mesa may have rounded corners, therebypreventing current crowding at the corners thereof.

The second electrode pad may include a plurality of fingers. Since thesecond electrode pad has the plurality of fingers, the light emittingdevice may have improved bonding strength by preventing voids from beingtrapped in the electrode pads upon flip-chip bonding of the lightemitting device to a submount or a printed circuit board.

The first electrode pad may also include a plurality of fingers. Thefingers of the first electrode pad and the fingers of the secondelectrode pad may be arranged to oppose each other and be alternatelyarranged. Accordingly, the fingers may be formed to have a longerlength, thereby assisting in current spreading.

In some exemplary embodiments the exterior contact portion may have aring shape surrounding the mesa. Alternatively, the first contact layermay include a plurality of exterior contact portions separated from eachother. The plurality of exterior contact portions may be separated fromeach other near the corners of the mesa. In this manner, the lightemitting device may further prevent current crowding near the corners ofthe mesa.

The interior contact portions may include elongated contact portions. Inthis manner, the light emitting device may facilitate current spreadingin the first conductive type semiconductor layer.

The light emitting device may further include an upper insulation layerdisposed on the first contact layer and having a first openingoverlapping the first contact layer and a second opening overlapping thesecond contact layer. The first electrode pad and the second electrodepad may be electrically connected to the first contact layer and thesecond contact layer through the first and second openings of the upperinsulation layer, respectively. The upper insulation layer may cover thefirst contact layer o protect the first contact layer.

The light emitting device may further include an intermediate connectionlayer disposed between the second contact layer and the second electrodepad, and surrounded by the first contact layer. The second opening ofthe upper insulation layer may expose the intermediate connection layer,the second electrode pad may be connected to the intermediate connectionlayer through the second opening of the upper insulation layer, and theintermediate connection layer may be connected to the second contactlayer.

The first contact layer and the intermediate connection layer mayinclude an Al layer as the same material layer and a Ti uppermost layer.The Al layer may be used as a reflective layer and the Ti uppermostlayer may reinforce bonding strength with the upper insulation layerdisposed thereon.

The Ti uppermost layer may be substantially disposed between aninterface between the first contact layer and the upper insulationlayer, and an interface between the intermediate connection layer andthe upper insulation layer.

The second electrode pad may be substantially disposed on theintermediate connection layer to have a narrower area than theintermediate connection layer.

The light emitting device may further include a lower insulation layercovering the mesa to insulate the first contact layer from the mesa andinterposed between the second contact layer and the intermediateconnection layer. The lower insulation layer may expose the firstconductive type semiconductor layer such that the exterior contactportion and the interior contact portions contact the first conductivetype semiconductor layer, and expose the second contact layer such thatthe intermediate connection layer is connected to the second contactlayer.

The lower insulation layer may include a silicon nitride layer and asilicon oxide layer, and the upper insulation layer may include asilicon oxide layer.

The light emitting device may further include a substrate on which thefirst conductive type semiconductor layer is disposed, and may furtherinclude a wavelength conversion layer covering a lower surface and aside surface of the substrate.

In accordance with a further exemplary embodiment, a light emittingmodule may include a submount mounted on a printed circuit board, andthe light emitting device as set forth above, the light emitting devicebeing flip-bonded to the submount.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject matter ofinvention, which is defined solely by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1A is a plan view of a light emitting device including a bondingpad constructed, according to the principles of the invention havingbonding pads or electrodes with particular spaced structures accordingto some exemplary embodiments of the invention.

FIG. 1B is a cross-sectional view of the light emitting device takenalong line A′-A of FIG. 1A.

FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 8 are plan views oflight emitting devices including electrodes having various shapes,according to exemplary embodiments of the invention.

FIG. 7A is a cross-sectional view of the light emitting device takenalong line B-B′ of FIG. 3.

FIG. 7B is a cross-sectional view of the light emitting device takenalong line C-C′ of FIG. 3.

FIG. 9, FIG. 10, FIG. 11, FIG. 12, FIG. 13, and FIG. 14 are plan viewsand sectional views of a light emitting device, according to otherexemplary embodiment of the invention.

FIG. 15 and FIG. 16 are plan views of a light emitting device, accordingto a further exemplary embodiment of the invention.

FIG. 17 is a schematic plan view of a light emitting device, accordingto other exemplary embodiments of the invention having spaced structuresto minimize manufacturing defects.

FIG. 18 is a cross-sectional view of the light emitting device takenalong line A-A′ of FIG. 1.

FIG. 19 is an enlarged sectional view of the light emitting device shownin FIG. 1.

FIG. 20 is a cross-sectional view of the light emitting device takenalong line B-B′ of FIG. 3.

FIG. 21, FIG. 22, FIG. 23, FIG. 24, and FIG. 25 are plan viewsillustrating a method of manufacturing a light emitting device,according to another exemplary embodiment of the invention.

FIG. 26 is a schematic plan view of an exterior contact portion andinterior contact portions of a light emitting device, according to yetanother exemplary embodiment of the invention.

FIG. 27 is a schematic plan view of a modification of the exteriorcontact portion of a light emitting device, according to anotherexemplary embodiment of the invention.

FIG. 28 is a schematic plan view of a modification of the interiorcontact portions of a light emitting device, according to an exemplaryembodiment of the invention.

FIG. 29 is a schematic plan view of a modification of a first electrodepad of a light emitting device, according to an exemplary embodiment ofthe invention.

FIG. 30 is a schematic sectional view of a light emitting deviceincluding a wavelength conversion layer constructed according to theprinciples of the invention.

FIG. 31 is a schematic sectional view of a light emitting module,according to an exemplary embodiment of the invention.

FIG. 32A and FIG. 32B are a schematic plan view and a schematic rearview of a submount substrate of a light emitting module constructed,according to exemplary embodiments of the invention, respectively.

FIG. 33 is an exploded perspective view of an exemplary lightingapparatus to which a light emitting device according to exemplaryembodiments of the invention is applied.

FIG. 34 is a sectional view of an exemplary display device to which alight emitting device according to exemplary embodiments of theinvention is applied.

FIG. 35 is a sectional view of an exemplary display device to which alight emitting device according to exemplary embodiments of theinvention is applied.

FIG. 36 is a sectional view of an exemplary headlight to which a lightemitting device according to exemplary embodiments of the invention isapplied.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments. It is apparent, however,that various exemplary embodiments may be practiced without thesespecific details or with one or more equivalent arrangements. In otherinstances, well-known structures and devices are shown in block diagramform in order to avoid unnecessarily obscuring various exemplaryembodiments.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail ofvarious exemplary embodiment. Therefore, unless otherwise specified, thefeatures, components, modules, layers, films, panels, regions, and/oraspects of the various illustrations may be otherwise combined,separated, interchanged, and/or rearranged without departing from thedisclosed exemplary embodiments. Further, in the accompanying figures,the size and relative sizes of layers, films, panels, regions, etc., maybe exaggerated for clarity and descriptive purposes. When an exemplaryembodiment may be implemented differently, a specific process order maybe performed differently from the described order. For example, twoconsecutively described processes may be performed substantially at thesame time or performed in an order opposite to the described order.Also, like reference numerals denote like elements.

When an element or layer is referred to as being “on,” “connected to,”or “coupled to” another element or layer, it may be directly on,connected to, or coupled to the other element or layer or interveningelements or layers may be present. When, however, an element or layer isreferred to as being “directly on,” “directly connected to,” or“directly coupled to” another element or layer, there are no interveningelements or layers present. Further, the x-axis, the y-axis, and thez-axis are not limited to three axes of a rectangular coordinate system,and may be interpreted in a broader sense. For example, the x-axis, they-axis, and the z-axis may be perpendicular to one another, or mayrepresent different directions that are not perpendicular to oneanother. For the purposes of this disclosure, “at least one of X, Y, andZ” and “at least one selected from the group consisting of X, Y, and Z”may be construed as X only, Y only, Z only, or any combination of two ormore of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various elements, components, regions, layers, and/or sections,these elements, components, regions, layers, and/or sections should notbe limited by these terms. These terms used to distinguish one element,component, region, layer, and/or section from another element,component, region, layer, and/or section. Thus, a first element,component, region, layer, and/or section discussed below could be termeda second element, component, region, layer, and/or section withoutdeparting from the teachings of the present disclosure.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for descriptive purposes, and,thereby, to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the drawings. Spatiallyrelative terms are intended to encompass different orientations of anapparatus in use, operation, and/or manufacture in addition to theorientation depicted in the drawings. For example, if the apparatus inthe drawings is turned over, elements described as “below” or “beneath”other elements or features would then be oriented “above” the otherelements or features. Thus, the exemplary term “below” can encompassboth an orientation of above and below. Furthermore, the apparatus maybe otherwise oriented (e.g., rotated 90 degrees or at otherorientations), and, as such, the spatially relative descriptors usedherein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof.

Various exemplary embodiments are described herein with reference tosectional illustrations that are schematic illustrations of idealizedexemplary embodiments and/or intermediate structures. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should not beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the drawings are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

Various exemplary embodiments are described herein with reference tosectional illustrations that are schematic illustrations of idealizedexemplary embodiments and/or intermediate structures. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should not beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to not planted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the drawings are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to be limiting.

FIG. 1A is a plan view of a light emitting device including a bondingpad constructed having a particular structure according to one exemplaryembodiment of the invention. FIG. 1B is a cross-sectional view of thelight emitting device taken along line A′-A of FIG. 1A.

Referring to FIG. 1A and 1B, a light emitting device according to theexemplary embodiment includes electrodes having a particular structurein which a first conductive type semiconductor layer 111, an activelayer 112, and a second conductive type semiconductor layer 113 areformed on a substrate 101 such that the active layer 112 is interposedbetween an n-type semiconductor layer 111 and a p-type semiconductorlayer 113.

The substrate 101 may be formed using a typical material, such asaluminum oxide (Al₂O₃), silicon carbide (Sic), silicon (Si), galliumarsenide (GaAs), gallium nitride (GaN), zinc oxide (ZnO), galliumphosphide (GaP), indium phosphide (InP), and germanium (Ge), known inthe art. A roughness pattern may be formed on upper and/or lowersurfaces of the substrate 101. The roughness pattern may have a shapeselected from among a stripe shape, a lens shape, a column shape, aconical shape, and the like.

The first conductive type semiconductor layer 111 includes asemiconductor layer doped with a first conductive type dopant. The firstconductive type semiconductor layer 111 may include at least one ofgallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN),indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), andindium aluminum gallium nitride (InAlGaN). The first conductive typesemiconductor layer 111 may be an n-type semiconductor layer, the firstconductive type dopant may include at least one n-type dopant, such asselected from among Si, Ge, Sn, Se, and Te.

The active layer 112 may have a single quantum well structure or amulti-quantum well (MQW) structure. More particularly, the active layermay be formed of a group III-group V compound semiconductor, that is, atleast one of GaN, InN, AlN, InGaN, AlGaN, and InAlGaN. For example, theactive layer 112 may have a structure, in which InGaN well layers andGaN barrier layers are alternately stacked one above another. The activelayer 112 may generate light through recombination of carriers suppliedfrom the first conductive type semiconductor layer 111 and carrierssupplied from the second conductive type semiconductor layer 113. Whenthe first conductive type semiconductor layer 111 is an n-typesemiconductor layer, the carriers supplied from the first conductivetype semiconductor layer 111 may be electrons, and when the secondconductive type semiconductor layer 113 is a p-type semiconductor layer,the carriers supplied from the second conductive type semiconductorlayer 113 may be holes.

The second conductive type semiconductor layer 113 includes asemiconductor layer doped with a second conductive type dopant, and maybe composed of a single layer or multiple layers. The second conductivetype semiconductor layer 113 may be formed of at least one of GaN, InN,AlN, InGaN, AlGaN, and InAlGaN. The second conductive type semiconductorlayer 113 may be a p-type semiconductor layer, and the second conductivetype dopant may include at least one p-type dopant, such as selectedfrom among Mg, Zn, Ca, Sr, and Ba.

The light emitting device according to the exemplary embodiment mayfurther include a non-doped layer or other buffer layers, in order toimprove crystal quality. When the second conductive type semiconductorlayer 113 is the p-type semiconductor layer, the light emitting devicemay include layers that miry perform various functions, such as anelectron blocking layer (not shown) formed between the active layer 112and the second conductive type semiconductor layer 113.

A nitride-based semiconductor stack 110 may include exposure regions “e”that partially expose the first conductive type semiconductor layer 111,such that the first conductive type semiconductor layer 111 iselectrically connected to a first electrode 140 through the exposureregions “e”. Current spreading efficiency and light emission patterns ofthe light emitting device may be adjusted depending upon the location,shape, and number of the exposure regions “e”. The exposure regions “e”may be formed by a photolithography and etching technology. For example,the exposure regions “e” may be formed by defining etching regions usinga photoresist, and etching the second conductive type semiconductorlayer 113 and the active layer 112 by dry etching, such as inductivelycoupled plasma (ICP) etching.

FIG. 1B shows one example of the exposure regions “e” having a holeshape that is formed through the active layer 112 and the secondconductive type semiconductor layer 113. The first conductive typesemiconductor layer 111 is electrically connected to the first electrode140 through the holes. The holes may be arranged regularly orirregularly. Current spreading efficiency and light emission patterns ofthe light emitting device may be adjusted depending upon the location,shape, and number of the holes in the exposure regions “e”.

A second electrode 120 may be disposed on the second conductive typesemiconductor layer 113, and electrically connected to the secondconductive type semiconductor layer 113. The second electrode 120includes a reflective metal layer 121 and may further include a barriermetal layer 122, which may cover an upper surface and side surfaces ofthe reflective metal layer 121. For example, the barrier metal layer 122may be formed to cover the upper and side surfaces of the reflectivemetal layer 121 by forming a pattern of the reflective metal layer 121,followed by forming the barrier metal layer 122 thereon. Moreparticularly, the reflective metal layer 121 may be formed throughdeposition and patterning of Ag, Ag alloy, Ni/Ag, NiZn/Ag, or TiO/Aglayers.

The barrier metal layer 122 may be formed of Ni, Cr, Ti, Pt, orcombinations thereof. The barrier metal layer 122 prevents metallicmaterials of the reflective metal layer 121 from diffusing or beingcontaminated. Furthermore, the second electrode 120 may include indiumtin oxide (ITO), zinc oxide (ZnO), and the like. ITO or ZnO is a metaloxide having high light transmittance, and thus, may improve luminousefficacy of the light emitting device by suppressing light absorption bythe second electrode 120.

The first electrode 140 may be electrically connected to the firstconductive type semiconductor layer 111. The first electrode 140 maycover the nitride-based semiconductor stack 110. In addition, the firstelectrode 140 may include an opening 140 b that exposes the secondelectrode 120. The first electrode 140 may be formed over substantiallythe entirety of a growth substrate 101, excluding the opening 140 b.Accordingly, current may easily spread over substantially the entiretyof the growth substrate 101 through the first electrode 140. The firstelectrode 140 may include a highly reflective metal layer, such as an Allayer, which may be formed on a bonding layer, such as Ti Cr, or Nilayer. The light emitting device may further include a protective layerof Ni, Cu, or Au having a single layer structure or a combination layerthereof on the highly reflective metal layer. The first electrode 140may have a multilayer structure of, for example, Ti/Al/Ti/Ni/Au. Thefirst electrode 140 may be formed through deposition and patterning of ametallic material on the nitride-based semiconductor stack 110.

The light emitting device according to this exemplary embodiment mayfurther include a lower insulation layer 130. The lower insulation layer130 covers an upper surface of the nitride-based semiconductor stack 110and an upper surface and side surfaces of the second electrode 120. Thelower insulation layer 130 is interposed between the nitride-basedsemiconductor stack 110 and the first electrode 140 to insulate thefirst electrode 140 from the second electrode 120. The lower insulationlayer 130 has openings 130 a, 130 b that may provide electricalconnection to the first conductive type semiconductor layer 111 and thesecond conductive type semiconductor layer 113 in a predeterminedregion. For example, the lower insulation layer 130 may include theopening 130 a that exposes the first conductive type semiconductor layer111 and the opening 130 b that exposes the second electrode 120. Theopening 130 b of the lower insulation layer 130 may be narrower than theopening 140 b of the first electrode 140. The lower insulation layer 130may include an oxide, such as silicon oxide (SiO₂), a nitride, such assilicon nitride (SiN_(x)), or an insulation material, such as magnesiumfluoride (MgF₂) through chemical vapor deposition (CVD) or the like. Thelower insulation layer 130 may have a single layer or multiple layersstructure. Furthermore, the lower insulation layer 130 may include adistributed Bragg reflector (DBR), in which low refractivity materiallayers and high refractivity material layers are alternately stacked oneabove another. For example, an insulation layer having high reflectivitymay be formed by stacking SiO₂/TiO₂ layers or SiO₂/Nb₂O₅ layers.

The light emitting device according to this exemplary embodiment mayfurther include an upper insulation layer 150. The upper insulationlayer 150 may cover a portion of the first electrode 140. The upperinsulation layer 150 may include an opening 150 a that exposes the firstelectrode 140, and an opening 150 b that exposes the second electrode120. The opening 150 b of the upper insulation layer 150 may be narrowerthan the opening 140 b of the first electrode 140 and the opening 130 bof the lower insulation layer 130. Accordingly, the upper insulationlayer 150 may cover not only a sidewall of the opening 140 b of thefirst electrode 140 but also a sidewall of the opening 130 b of thelower insulation layer 130 may be covered by the upper insulation layer150. In this manner, the light emitting device protect the secondelectrode 120 from infiltration of moisture and the like moreeffectively. In particular, even when the second electrode 120 does notinclude the barrier metal layer 122, external moisture may be preventedfrom infiltrating the reflective metal layer of the second electrode 120by the upper insulation layer 150. However, it should be understood thatthe present disclosure is not limited thereto and the upper insulationlayer 150 may be alternatively formed through deposition and patterningof an oxide insulation layer, a nitride insulation layer, or a polymer,such as polyimide, Teflon, and Parylene, on the first electrode 140.

A bonding pad of the light emitting device according to the exemplaryembodiment may include first bonding pads 200 a and second bonding pads200 b electrically connected to the first electrode 140 and the secondelectrode 120, respectively. Referring to FIG. 1B, each of the firstbonding pads 200 a may be connected to the first electrode 140 through afirst connection electrode formed in the opening 150 a of the upperinsulation layer 150, and each of the second bonding pads 200 b may beconnected to the second electrode 120 through a second connectionelectrode formed in the opening 150 b of the upper insulation layer 150.The first bonding pads 200 a and the second bonding pads 200 b mayconnect the first electrode 140 and the second electrode 120 to themount substrate (not shown). The first bonding pads 200 a and the secondbonding pads 200 b may be simultaneously formed by the same process, forexample, photolithography and etching technology, or lift-offtechnology. The first bonding pads 200 a and the second bonding pads 200b may include a bonding layer of, for example, Ti, Cr, or Ni, and ahighly conductive metal layer of, for example, Al, Cu, Ag, or Au.

In the light emitting device including the bonding pads 200 a and 200 baccording to this exemplary embodiment, the active layer 112 dividedinto several sections may share a single first conductive typesemiconductor layer 111.

When the first bonding pads 200 a and the second bonding pads 200 boccupy a substantial area of solder ball contactable regions 210 tofacilitate bonding between a mounting substrate and the bonding pads 200a and 200 b, reliability of the light emitting device may bedeteriorated due to the voids generated during the reflow process.

According to an exemplary embodiment of the invention, as shown in FIG.1 to FIG. 6, the light emitting device including electrodes may have aconfiguration, in which the bonding pads 200 a and 200 b are soldered toa mounting substrate (not shown) and are electrically connected to thefirst conductive type semiconductor layer 111 and the second conductivetype semiconductor layer 113 via connection electrodes, respectively.Two or more bonding pads 200 a and 200 b having a generally rectangularshape (as defined below) are formed in each of the solder ballcontactable regions 210. At least two of the bonding pads 200 a and 200b oppose each other. A non-conductive region 220 may be disposed betweenthe at least two adjacent bonding pads 200 a and 200 b.

As used herein, the solder ball contactable region 210 means a portionof the light emitting device that may contact a solder ball disposed onthe mounting substrate. When a solder is melted in a reflow process, thesolder ball contactable region 210 may be included in a region occupiedby the molten solder.

The configuration and constituent elements of the first bonding pad 200a may be substantially similar to those of the second bonding pad 200 b.As such, the bonding pad according to exemplary embodiments of theinvention will be described with reference to the first bonding pad 200a, for convenience of description.

As used herein, the “generally rectangular” or “rectangular” shape ofthe bonding pad 200 a refers to a bonding pad having an elongate shape,length of greater than its width, such as an electrode. The rectangularbonding pad 200 a may have at least or more rounded corners. Inaddition, as used herein, the non-conductive region 220 is a region inwhich the bonding pads 200 a are not formed, and to which the upperinsulation layer 150 is exposed. More particularly, the non-conductiveregion 220 may correspond to regions defined by a step or space betweenthe upper insulation layer 150 and a layer of the bonding pads 200 a.

As used herein, the “bonding pads are opposed each other” means anystructure, in which the bonding pads 200 a and 200 b face each other bybeing disposed generally parallel to each other or facing each othereven if not disposed parallel to each other. More particularly, thebonding pads 200 a of the light emitting device include two or moregenerally rectangular bonding pads 200 a, in which at least two of thetwo or more bonding pads 200 a are opposed to face each other, and thenon-conductive region 220 is disposed between the at least two opposedbonding pad 200 a, to reduce the occurrence of voids during the reflowprocess. More particularly, as shown in FIG. 1A, at least two of the twoor more bonding pads 200 a may be separated from each other.

Referring to FIG. 2, at least two of the two or more line-shaped bondingpads 200 a may be connected to each other.

Referring to FIGS. 3 to 6, the rectangular bonding pads 200 a may beconnected to each other at any location via a connection portion to formvarious shapes such as “E”, “W”, and “H” or other shapes. For example,referring to FIG. 3, all of four bonding pads 200 a are connected toeach other through three connection portions. More particularly, asshown in FIG. 3 to FIG. 6, when the number of two or more bonding pads200 a is n (n≥2), and the light emitting device includes at least n−1connection portions, all of the rectangular bonding pads 200 a may beconnected to each other so as to extend from a common base or connectionpoint.

According to an exemplary embodiment of the invention, the bonding pads200 a may be alternatively connected to each other via a greater numberof connection portions, so long as the non-conductive region 220 isdisposed between two opposed bonding pads 200 a.

More particularly, the bonding pad 200 a of the light emitting deviceincludes two or more bonding pads 200 a, in which at least two of theline-shaped bonding pads 200 a are generally opposed to each other, andthe non-conductive region 220 is disposed between the two opposedbonding pads 200 a. In this manner, an upper portion of the insulationlayer 150 is exposed, and provides a space defined by the step betweenthe insulation layer 150 and the layer of the bonding pads 200 a, whichmay reduce the occurrence of large voids during a reflow process.

FIGS. 7A and 7B are cross-sectional views of the light emitting devicetaken along lines B-B′ and C-C′ of FIG. 3

Referring to FIG. 7A, the second bonding pads 200 b are generallyrectangular bonding pads 200 b and the non-conductive region 220 isinterposed between the opposed bonding pads 200 b. In this manner, aspace defined by a step between the insulation layer 150 and a layer ofthe bonding pad 200 b is formed therebetween, such that by-products,such as any unwanted substances generated during soldering or fusing ina state of gas, liquid, liquid, etc., generated during the reflowprocess may escape into the space, thereby improving reliability of thelight emitting device.

Referring to FIG. 7B, the first bonding pads 200 a are generallyrectangular bonding pads 200 a and the non-conductive region 220 isinterposed between the opposed bonding pads 200 a. In this manner, aspace defined by the step between the insulation layer 150 and the layerof the bonding pad 200 a is formed therebetween, such that voidsgenerated during the reflow process may escape into the space, therebyimproving reliability of the light emitting device.

The line-shaped bonding pads 200 a may have a width “t” of 200 μm orless. When the width “t” of the bonding pads 200 a may be less isgreater than 200 μm, a distance from a location where voids aregenerated in the solder ball contactable region 210 to thenon-conductive region 220 becomes too long within the bonding pad 200 a.Accordingly, the voids may be trapped in the bonding pads 200 a, ratherthan escaping from the bonding pads 200 a, which may deterioratereliability of the light emitting device, such as poor connection to themounting substrate, deterioration in heat dissipation, and the like.

In addition, the line-shaped bonding pads 200 a may have a width “t” of40 μm or more. When the width “t” of the line-shaped bonding pads 200 ais less than 40 μm, current injection into the bonding pads 200 a may belowered, which may deteriorate luminous efficacy of the light emittingdevice.

The ratio of the area of the bonding pads 200 a to the area of thesolder ball contactable regions 210 may be 40% or more. When the area ofthe line-shaped bonding pads 200 a is less than 40% of the area of thesolder ball contactable regions 210, current injection into the bondingpads 200 a may be lowered, which may deteriorate luminous efficacy ofthe light emitting device. It is contemplated that the structure of thebonding pad according to exemplary embodiments of the invention may bemodified in various ways to prevent the occurrence of voids having alarger diameter than the width of electrodes.

Referring to FIG. 8, in a light emitting device including electrodesaccording to an exemplary embodiment of the invention, bonding pads 200a and 200 b are soldered to a mounting substrate, and are electricallyconnected to the first electrode 140 and the second electrode 120connected to the first conductive type semiconductor layer and thesecond conductive type semiconductor layer via the connectionelectrodes, respectively. The bonding pads 200 a is disposed on aportion of a solder ball contactable region 210, and a non-conductivepattern 230, which may provide a path for void to escape, is formed inthe remaining portion of the solder ball contactable region 210.

As used herein, the non-conductive pattern 230 may correspond to aregion in which the bonding pads 200 a and 200 b are not formed, and towhich the upper insulation layer 150 is exposed. In this manner, a spacebetween the upper insulation layer 150 and a layer of the bonding pads200 a and 200 b may be formed, such that voids generated during thereflow process may escape into the space formed thereby.

In particular, in the light emitting device according to the exemplaryembodiment, the bonding pads 200 a and 200 b are formed in a portion ofthe solder ball contactable region 210, and the non-conductive pattern230 is formed in the remaining portion of the solder ball contactableregion 210, such that voids may escape through the non-conductivepattern 230, which may reduce the occurrence of voids during the reflowprocess.

More particularly, as shown in FIG. 8, the non-conductive pattern 230may be formed within a distance of 200 μm from a point P within thebonding pads 200 a and 200 b, towards a periphery of the solder ballcontactable region 210. In this manner, voids may escape from thebonding pads 200 b through the non-conductive pattern 230. Inparticular, if the distance from the point P within the electrodeexceeds about 200 μm, it may be difficult for voids to escape from thebonding pads 200 b. Accordingly, the non-conductive pattern 230 may beformed in the other portion of the solder ball contactable region 210.

The non-conductive pattern 230 may have a tapered shape such astrapezoidal that gradually widens towards the periphery of the solderball contactable region 210. In this manner, the voids may easily escapefrom the bonding pads 200 b.

The ratio of the area of the bonding pads 200 a and 200 b to an area ofthe solder ball contactable regions 210 may be 40% or more. If the areaof the bonding pads 200 a and 200 b is less than 40% of the area of thesolder ball contactable regions 210, current injection into theelectrodes may be lowered, which may deteriorate luminous efficacy ofthe light emitting device.

FIG. 9 to FIG. 14 are plan views and sectional views of a light emittingdevice according to an exemplary embodiment of the invention. Inparticular, FIG. 9 is a plan view of the light emitting device accordingto an exemplary embodiment of the invention. FIG. 10 is a plan view ofthe light emitting device, in which bonding pads 200 a and 200 b areomitted for convenience of description. FIG. 11 is a plan view of thelight emitting device, in which the bonding pads 200 a and 200 b, anupper insulation layer 150, a first electrode 140 and a lower insulationlayer 130 are omitted for convenience of description. FIG. 12 is across-sectional view taken along line A-A′ of FIG. 9 to FIG. 11. FIG. 13is a cross-sectional view taken along line B-B′ of FIG. 9 to FIG. 11.FIG. 14 is a cross-sectional view taken along line C-C′ of FIG. 9 toFIG. 11.

The light emitting device according to the exemplary embodiment hasdifferent structures of bonding pads 200 a and 200 b, and anitride-based semiconductor stack 110, as compared to those of the lightemitting devices illustrated with reference to FIG. 1 to FIG. 8.Repeated description of substantially similar elements of the lightemitting device will be omitted.

Referring to FIG. 9 to FIG. 14, the light emitting device according tothe exemplary embodiment includes a nitride-based semiconductor stack110, a first electrode 140, a second electrode 120, a first bonding pad200 a, and a second bonding pad 200 b. The light emitting device mayfurther include a lower insulation layer 130, an upper insulation layer150, and a substrate 101. The light emitting device may have arectangular planar shape. In the exemplary embodiment, the lightemitting device have a substantially square planar shape and include afirst side surface 100 a, a second side surface 100 b, a third sidesurface 100 c opposite to the first side surface 100 a, and a fourthside surface 100 d opposite to the second side surface 100 b.

The nitride-based semiconductor stack 110 includes a first conductivetype semiconductor layer 111, an active layer 112 disposed on the firstconductive type semiconductor layer 111, and a second conductive typesemiconductor layer 113 disposed on the active layer 112. Thenitride-based semiconductor stack 110 includes exposure regions 110 a,110 b, and 110 c that partially expose the first conductive typesemiconductor layer 111. Current spreading efficiency and light emissionpatterns of the light emitting device may be adjusted depending upon thelocation, shape, and number of the exposure regions 110 a, 110 b, and110 c.

Referring to FIG. 11, the exposure regions 110 a, 110 b, and 110 c,through which the first conductive type semiconductor layer 111 ispartially exposed, may include holes. The holes may include a first hole110 a, a second hole 110 b, and a third hole 110 c. Each of the firsthole 110 a, the second hole 110 b, and the third hole 110 c may beformed in plural. The first holes 110 a may generally have a circular orpolygonal or irregular shape in plan view. The second holes 110 bgenerally have the same shape as the first holes 110 a. The third holes110 c may extend from the second holes 110 b in a predetermineddirection. The third holes 110 c may be connected to the second holes110 b. In addition, the third holes 110 c may have a smaller width thanthe first holes 110 a and the second holes 110 b.

For example, the first hole 110 a may have a circular shape in plan viewand are formed in plural. The third hole 110 c may extend from e secondhole 100 b from the first side surface 100 a towards the third sidesurface 100 c and are formed in plural. At least a portion of the holes110 c may extend from a lower portion of the first bonding pad 200 a toa lower portion of the second bonding pad 200 b.

The second electrode 120 is disposed on the nitride-based semiconductorstack 110, and form ohmic contact with the second conductive typesemiconductor layer 113. The second electrode 120 may include openingsexposing the first and second holes 110 a and 110 b, and thus, areseparated from the first and second holes 110 a and 110 b.

The lower insulation layer 130 may cover the nitride-based semiconductorstack 110, and an upper surface and a side surface of the secondelectrode 120. In the exemplary embodiment, the lower insulation layer130 may include openings 130 a and 130 b, which may provide electricalconnection to the first conductive type semiconductor layer 111 and thesecond conductive type semiconductor layer 113 in a predeterminedregion. For example, the lower insulation layer 130 may include firstopenings 130 a that expose the first conductive type semiconductor layer111, and a second openings 1306 that expose the second electrode 120.

The first electrode 140 may be electrically connected to the firstconductive type semiconductor layer 111, and more particularly, formohmic contact with the first conductive type semiconductor layer 111.The first electrode 140 may be electrically connected to the firstconductive type semiconductor layer 111 through the first and secondholes 110 a and 110 b. In this manner, the current injection to thenitride-based semiconductor stack 110 through the first electrode 140may be adjusted by the location and shape of the first and second holes110 a and 110 b. Further, the first electrode 140 may include an opening140 b that exposes the second electrode 120. The first electrode 140 maybe formed substantially over the entirety of a growth substrate 101,excluding the opening 140 b.

The upper insulation layer 150 may cover a portion of the firstelectrode 140. The upper insulation layer 150 may include third openings150 a that expose the first electrode 140, and fourth openings 150 bthat expose the second electrode 120. The fourth opening 150 b of theupper insulation layer 150 may be narrower than the openings 140 b ofthe first electrode 140 and the openings 130 b of the lower insulationlayer 130. In the exemplary embodiment, the upper insulation layer 150covers a portion of the first electrode 140 disposed in the third hole110 c. In this manner, the third openings 150 a of the upper insulationlayer 150 may partially expose the first electrode 140 disposed on thefirst holes 110 a and/or the second holes 110 b.

The first bonding pad 200 a and the second bonding pad 200 b may beelectrically connected to the first electrode 140 and the secondelectrode 120, respectively. Referring to FIG. 10, the first bonding pad200 a may contact the first electrode 140 through the third openings 150a, and the second bonding pad 200 b may contact the second electrode 150through the fourth openings 150 b.

The first and second bonding pads 200 a and 200 b include anon-conductive region 220 disposed within a solder ball contactableregion 210. Each of the first and second bonding pads 200 a and 200 bmay include a portion disposed generally parallel to one side surface ofthe light emitting device, and at least one protrusion 240 protrudingfrom the portion. For example, referring back to FIG. 9, the firstbonding pad 200 a may include a portion disposed generally parallel tothe first side surface 100 a of the light emitting device, and threeprotrusions 240 protruding from the portion. The non-conductive region220 of the first bonding pad 200 a may be disposed between the threeprotrusions 240. Similarly, the second bonding pad 200 b may include aportion disposed generally parallel to the third side surface 100 c ofthe light emitting device, and three protrusions 240 protruding from theportion. The non-conductive region 220 of the first bonding pad 200 bmay be disposed between the three protrusions 240. In this manner, thelight emitting device including the non-conductive regions 220 mayreduce or prevent the occurrence of voids during soldering.

Width t2 of the portion of each of the first and second bonding pads 200a and 200 b, which are disposed generally parallel to one side surfaceof the light emitting device, may be the same as or different from widtht1 of the protrusions 240. The widths t1 and t2 may be in the range from40 μm to 200 μm.

The first bonding pad 200 a may partially cover a portion of the firstelectrode 140 that contacts the first conductive type semiconductorlayer 111, through the exposure regions 110 a, 110 b, and 110 c. Moreparticularly, the first bonding pad 200 a may be formed to coverportions of the first electrode 140 disposed in the first holes 110 aand the second holes 110 b, which have relatively large widths. Forexample, the protrusions 240 of the first bonding pad 200 a may bedisposed corresponding to locations of the first holes 110 a and thesecond holes 110 b.

Due to heat or stress during soldering or other heat fusion process,stress and strain may be applied to an interface between the firstconductive type semiconductor layer 111 and the first electrode 140through the exposure regions 110 a, 110 b, and 110 c, by which the firstconductive type semiconductor layer 111 is exposed. The stress andstrain may cause delamination of the first electrode 140 from the firstconductive type semiconductor layer 111, which may increase forwardvoltage (V_(f)) of the light emitting device or inefficient currentspreading. As such, reliability of the light emitting device maydeteriorate due to electrical and optical properties thereof.

According to the exemplary embodiment, the portions of the firstelectrode 140 disposed in the first holes 110 a and the second holes 110b are covered by the first bonding pad 200 a, which may more firmlysecure the first electrode 140. In this manner, the light emittingdevice may prevent delamination of the first electrode 140 from thefirst conductive type semiconductor layer 111 more efficiently duringsoldering. In addition, when the first holes 110 a and the second holes110 b have greater widths than the third holes 110 c, reduction ofcurrent injection efficiency through the first holes 110 a and thesecond holes 110 b may deteriorate properties of the light emittingdevice to a greater degree. According to the exemplary embodiment, theportions of the first electrode 140 disposed in the first holes 110 aand the second holes 110 b are covered by the first bonding pad 200 a,which may improve reliability of the light emitting device moreeffectively.

Referring back to FIG. 9 to FIG. 14, the first bonding pad 200 a and thesecond bonding pad 200 b may be formed to be generally symmetrical inshape. The protrusions 240 of the first and second bonding pads 200 aand 200 b, however, may be alternatively modified in various ways. Forexample, referring to FIG. 15 and FIG. 16, the protrusions 240 of thefirst bonding pad 200 a may be formed to be disposed in the first andsecond holes 110 a and 110 b. Accordingly, the first bonding pad 200 amay include three protrusions 240 protruding towards the second bondingpad 200 b, in which the non-conductive region 220 is disposed betweenthe three protrusions 240. Likewise, the second bonding pad 200 b mayinclude three protrusions 240 protruding towards the non-conductiveregion 220 of the first bonding pad 200 a. In this manner, a path fordischarging voids in the reflow process may be changed by changing thelocations of the protrusions 240.

It is contemplated that a configuration of the first and second bondingpads 200 a and 200 b, however, may alternatively modified, asillustrated with reference to FIG. 1 to FIG. 8. For example, the firstand second bonding pads 200 a and 200 b may be formed to cover the firstholes 110 a and the second holes 110 b, thereby improving reliability ofthe light emitting device.

FIG. 17 is a schematic plan view of a light emitting device 10 accordingto an exemplary embodiment of the invention. FIG. 18 is across-sectional view of the light emitting device taken along line A-A′of FIG. 17. FIG. 19 is an enlarged sectional view of the light emittingdevice shown in FIG. 17. FIG. 20 is a cross-sectional view of the lightemitting device taken along line B-B′ of FIG. 17.

Referring to FIG. 17 to FIG. 20, the light emitting device 10 includes afirst conductive type semiconductor layer 23, a mesa M, an active layer25, a second conductive type semiconductor layer 27, a first contactlayer 35 a, a second contact layer 31, a first electrode pad 39 a, and asecond electrode pad 39 b. The light emitting device 10 may furtherinclude a substrate 21, a lower insulation layer 33, an upper insulationlayer 37, and an intermediate connection layer 35 b.

The substrate 21 may be any substrate suitable for growth of the firstconductive type semiconductor layer 23. For example, the substrate 21may be selected from among a sapphire substrate, a gallium nitridesubstrate, an aluminum nitride substrate, and a silicon carbidesubstrate, or may be a patterned sapphire substrate.

As shown in FIG. 17, the substrate 21 may have a generally rectangularor square shape and has side surfaces. For example, the substrate 21 mayhave a square shape having a size of 1000 μm×1000 μm or 700 μm×700 μm,or may have a rectangular shape having a size of 1000 μm×1000 μm or 700μm×700 μm.

A semiconductor stack structure 30 is disposed on 21. The semiconductorstack structure 30 includes the first conductive type semiconductorlayer 23, the active layer 25, and the second conductive typesemiconductor layer 27.

The first conductive type semiconductor layer 23 may be disposed over anupper surface of the substrate 21. The first conductive typesemiconductor layer 23 is a layer grown on the substrate 21. The firstconductive type semiconductor layer 23 may be a gallium nitridesemiconductor layer doped with dopants, for example, Si. A concentrationof the dopants may be in a range of, for example, 1E19/cm³ to 2E19/cm³.

The mesa M is disposed on the first conductive type semiconductor layer23. The mesa M may be substantially disposed inside a region surroundedby the first conductive type semiconductor layer 23. In this manner,regions near an edge of the first conductive type semiconductor layer 23are exposed to the outside, rather than being covered by the mesa M.

The mesa M includes the second conductive type semiconductor layer 27and the active layer 25, and may include a partial thickness of thefirst conductive type semiconductor layer 23. The active layer 25 isinterposed between the first conductive type semiconductor layer 23 andthe second conductive type semiconductor layer 27. The active layer 25may have a single quantum well structure or a multi-quantum wellstructure. In the active layer 25, the composition and thickness of welllayers therein may determine the wavelength of light generated by theactive layer 25. More particularly, the active layer 25 may emit UVlight, blue light, or green light through adjustment of the compositionof the well layers.

In the exemplary embodiment, the second conductive type semiconductorlayer 27 may be a gallium nitride semiconductor layer doped with p-typedopants, for example, Mg. Each of the first conductive typesemiconductor layer 23 and the second conductive type semiconductorlayer 27 may have a single layer or multiple layers structure, and mayinclude a super lattice layer.

As shown in FIG. 17, the mesa M may have a generally rectangular shapehaving rounded corners. The mesa M may also have a rectangular shapehaving rounded corners in a horizontal sectional view. The roundedcorners may prevent current crowding at the corners of the mesa M.

The mesa M includes through-holes 30 a therein. The first conductivetype semiconductor layer 23 is exposed through the through-holes 30 a.The through-holes 30 a may be regularly arranged in the mesa M. AlthoughFIG. 17 illustrates nine through-holes 30 a arranged in a matrix shapein the mesa M, it is contemplated that the number and arrangement of thethrough-holes 30 a may vary.

The second contact layer 31 is disposed on the mesa M and contact thesecond conductive type semiconductor layer 27. The second contact layer31 may be disposed on substantially the entire upper region of the mesaM. For example, the second contact layer 31 may cover 80% or more, forexample, 90% or more, of the upper region of the mesa M.

The second contact layer 31 may include a reflective metal layerconfigured to reflect light generated by the active layer 25 towards thesubstrate 21. For example, the second contact layer 31 may include metallayers of Ag/Ni/Ti/Pt that are sequentially stacked. Alternatively, thesecond contact layer 31 may be a transparent oxide layer, for example,indium tin oxide (ITO) or zinc oxide (ZnO).

The first contact layer 35 a covers the upper region of the mesa M. Thefirst contact layer 35 a includes an exterior contact portion 35 c 1 andinterior contact portions 35 c 2, to both of which contact the firstconductive type semiconductor layer 23. The exterior contact portion 35c 1 contacts the first conductive type semiconductor layer 23 near anedge of the substrate 21 in a ring shape along the periphery of the mesaM. The interior contact portions 35 c 2 contact portions of the firstconductive type semiconductor layer 23 exposed through the through-holes30 a. Shapes and locations of the exterior contact portion 35 c 1 andinterior contact portions 35 c 2 may be varied, which will be describedin more detail below.

The first contact layer 35 a may have an opening on the upper region ofthe mesa M, particularly, on the second contact layer 31, and theintermediate connection layer 35 b may be disposed inside the opening.In this manner, the intermediate connection layer 35 b may be surroundedby the first contact layer 35 a while being separated from the firstcontact layer 35 a. The first contact layer 35 a may be disposed on theentire upper region, side region, and exterior region of the mesa M. Theintermediate connection layer 35 b may be substantially disposed withinthe upper region of the mesa M.

The intermediate connection layer 35 b may be formed together with efirst contact layer 35 a. As such, the intermediate connection layer 35b and the first contact layer 35 a may include the same material. Thefirst contact layer 35 a and the intermediate connection layer 35 b mayinclude an Al layer, and may further include a Ti layer as an uppermostlayer. For example, the first contact layer 35 a and the intermediateconnection layer 35 b may include Al/Ti/Pt/Au/Ti/Ni/Au/Ti. As describedbelow, the uppermost Ti layer may be disposed at an interface of theupper insulation layer 37 to improve bonding strength of the upperinsulation layer 37. Alternatively, the Ti layer may be removed fromeach interface between the first electrode pad 39 a and the secondelectrode pad 39 b, and between the first contact layer 35 a and theintermediate connection layer 35 b. In this manner, Au layers of thefirst contact layer 35 a and the intermediate connection layer 35 b maybe exposed and bonded to metal layers, for example, Cu layers of thefirst electrode pad 39 a and the second electrode pad 39 b.

The lower insulation layer 33 is disposed between the first contactlayer 35 a and the mesa M, and insulates the first contact layer 35 afrom the mesa M and the second contact layer 31. As shown in FIG. 19,the lower insulation layer 33 may include a first insulation layer 32and a second insulation layer 34. The first insulation layer 32 maycover the mesa M around the second contact layer 31. The firstinsulation layer 32 may include, for example, silicon nitride, and maycover the side surface of the mesa M while covering a portion of thefirst conductive type semiconductor layer 23. The second insulationlayer 34 covers the first insulation layer 32 and a portion of thesecond contact layer 31. The second insulation layer 34 may include, forexample, silicon oxide.

The lower insulation layer 33 has openings 33 a formed inside thethrough-holes 30 a that expose the first conductive type semiconductorlayer 23. The interior contact portions 35 c 2 of the first contactlayer 35 a contact the first conductive type semiconductor layer 23through the openings 33 a. Further, the lower insulation layer 33 coversa portion of the first conductive type semiconductor layer 23 around themesa M while exposing the first conductive type semiconductor layer 23,such that the exterior contact portion 35 c 1 may contact the firstconductive type semiconductor layer 23.

The lower insulation layer 33 may be interposed between the intermediateconnection layer 35 b and the second contact layer 31, and may includeopenings 33 b that expose the second contact layer 31. Alternatively, aplurality of openings 33 b having a small size may be formed at variouslocations to expose the second contact layer 31, or a smaller number ofopenings or a single opening may be formed to expose the second contactlayer 31. The intermediate connection layer 35 b may be connected to thesecond contact layer 31 through the openings 33 b.

The upper insulation layer 37 is disposed on the first contact layer 35a and the intermediate connection layer 35 b. The upper insulation layer37 includes an opening 37 a that exposes the first contact layer 35 a,and an opening 37 b that exposes the intermediate connection layer 35 b.Alternatively, each openings 37 a and 37 b may be formed in plural toexpose the first contact layer 35 a and the intermediate connectionlayer 35 b, or a single opening 37 a and a single opening 37 b may beformed to expose the first contact layer 35 a and the intermediateconnection layer 35 b, respectively.

The upper insulation layer 37 may also cover the exterior contactportion 35 c 1 and an exposed surface near the edge of the substrate 21.The upper insulation layer 37 protects the first contact layer 35 a andthe intermediate connection layer 35 b by covering the first contactlayer 35 a and the intermediate connection layer 35 b.

The upper insulation layer 37 may include a single layer of siliconoxide. The upper insulation layer 37 may alternatively have a multilayerstructure including a silicon nitride layer and a silicon oxide layer,or a distributed Bragg reflector structure, in which silicon oxidelayers and titanium oxide layers are alternately stacked one aboveanother.

The first electrode pad 39 a is electrically connected to the firstcontact layer 35 a through the openings 37 a of the upper insulationlayer 37. The second electrode pad 39 b is electrically connected to theintermediate connection layer 35 b through the openings 37 b. In thismanner, the second electrode pad 39 b may be electrically connected tothe second contact layer 31 through the intermediate connection layer 35b. When the intermediate connection layer 35 b is omitted, the secondelectrode pad 39 b may be directly connected to the second contact layer31.

As shown in FIG. 17, the first electrode pad 39 a may have substantiallya rectangular shape. The second electrode pad 39 b may also have asubstantially rectangular shape. Alternatively, the second electrode pad39 b may have a section with elongate structures such as fingers, asshown in FIG. 17, which extend from a common base towards the firstelectrode pad 39 a.

The fingers may assist in preventing voids from being trapped under thesecond electrode pad 39 b upon mounting the second electrode pad 39 b ona printed circuit board or submount through conductive pastes. Moreparticularly, the voids may easily escape to regions between thefingers. Furthermore, the fingers may be disposed above and between thethrough-holes 30 a. In this manner, the fingers may not to overlap thethrough-holes 30 a, which may prevent formation of relatively largegrooves in the second electrode pad 39 b.

In the light emitting device 10 according to the exemplary embodiment,the upper surface of the mesa M has rounded corners, such that currentcrowding near the corners of the mesa M may be prevented. Furthermore,with the exterior contact portion 35 c 1 and the interior contactportions 35 c 2 of the first contact layer 35 a, the light emittingdevice 10 may have uniform current spreading in the first conductivetype semiconductor layer 23.

FIG. 21 to FIG. 25 are plan views illustrating a method of manufacturinga light emitting device according to an exemplary embodiment of theinvention.

Referring to FIGS. 18 and 21, a first conductive type semiconductorlayer 23, an active layer 25 and a second conductive type semiconductorlayer 27 are grown on a substrate 21.

For example, the first conductive type semiconductor layer 23 mayinclude an n-type gallium nitride layer and the second conductive typesemiconductor layer may include a p-type gallium nitride layer. Theactive layer may have a single quantum well structure or a multi-quantumwell structure, and may include a well layer and a barrier layer. Thewell layer may have compositional elements selected depending upon thewavelength of light, and may include, for example, indium galliumnitride (InGaN).

The first conductive type semiconductor layer 23, the active layer, andthe second conductive type semiconductor layer may be grown on a galliumnitride substrate 21 by metal organic chemical vapor deposition (MOCVD).

Then, a mesa M is formed on the first conductive type semiconductorlayer 23 by patterning the second conductive type semiconductor layerand the active layer. The mesa M includes the active layer and thesecond conductive type semiconductor layer, and may include somethickness of the first conductive type semiconductor layer 23. When themesa M is formed, through-holes 30 a may be formed through the secondconductive type semiconductor layer and the active layer to expose thefirst conductive type semiconductor layer 23.

The mesa M is disposed inside an edge region of the first conductivetype semiconductor layer 23, and the through-holes 30 a are disposedinside the mesa M region. The number of through-holes 30 a formed in themesa M may be varied.

A side surface of the mesa M may be slanted by, for example, photoresistreflow. A slanted side surface of the mesa M may improve extractionefficiency of light generated in the active layer. An upper surface ofthe mesa M has rounded corners. A horizontal cross-section of the mesa Malso may have rounded corners.

Referring to FIG. 22, a second contact layer 31 is formed on the mesa M.The second contact layer 31 forms ohmic contact with the secondconductive type semiconductor layer. The mesa M region around the secondcontact layer 31 and the first conductive type semiconductor layer 23may be covered by a first insulation layer 32.

More specifically, the first insulation layer 32 may be formed to coverthe first conductive type semiconductor layer 23 and the mesa M. Thefirst insulation layer 32 may include silicon nitride by, for example,chemical vapor deposition.

A photoresist pattern having an opening that exposes an upper region ofthe mesa M is formed on the first insulation layer 32. The opening mayhave a shape generally similar to the shape of the mesa M, and may beformed to be slightly smaller than the mesa M. A photoresist may bedeposited to cover edges of the mesa M. Further, the photoresist coversthe through-holes 30 a and the mesa M region around the through-holes 30a. A ⁻width of an entrance of the opening may be greater a width of abottom entrance of the opening. The photoresist pattern having such anopening may be formed by, for example, using a negative typephotoresist.

Thereafter, the first insulation layer 32 is etched using thephotoresist pattern as an etching mask, whereby the second conductivetype semiconductor layer is exposed. The first insulation layer 32 maybe subjected to, for example, wet etching.

Thereafter, a second contact layer 31 is formed. The second contactlayer 31 may be formed on the mesa M through a coating technology usinge-beam evaporation. The second contact layer 31 may include multiplemetal layers of, for example, Ag/Ni/Ti/Pt, or may include a transparentconductive material, such as ITO or ZnO. Then, the photoresist patternis removed. As a result, the mesa M is covered by the first insulationlayer 32 and the second contact layer 31. More particularly, the secondcontact layer 31 contacting the second conductive type semiconductorlayer remains on the mesa M, and the first insulation layer 32 remainsaround the second contact layer 31. The first insulation layer 32 maycover an exposed portion of the first conductive type semiconductorlayer 23.

Referring to FIG. 23, a lower insulation layer 33 is formed to cover themesa M and the first conductive type semiconductor layer 23 around themesa M. The lower insulation layer 33 has openings 33 a that expose thefirst conductive type semiconductor layer 23 in the through-holes 30 a,and also exposes the edge region of the first conductive typesemiconductor layer 23. Furthermore, the lower insulation layer 33 mayhave an opening 33 b that exposes the second contact layer 31. As shownin FIG. 23, the opening 33 b is disposed near one side of the mesa M.The opening 33 b may be formed in plural.

As shown in FIG. 19, the lower insulation layer 33 may include a firstinsulation layer 32 and a second insulation layer 34. The secondinsulation layer 34 covers the second contact layer 31 while coveringthe first insulation layer 32.

For example, the lower insulation layer 33 may be formed by forming thesecond insulation layer 34 to cover the first insulation layer 32 andthe second contact layer 31. The second insulation layer 34 may bepatterned together with the second insulation layer 34 and the firstinsulation layer 32 to form the openings 33 a and the openings 33 b.Then, the first insulation layer 32 and the second insulation layer 34remaining on the first conductive type semiconductor layer 23 around themesa M are removed to form the lower insulation layer 33.

The second insulation layer 34 may be formed of an oxide material, suchas SiO₂, by chemical vapor deposition (CVD) and the like, and theopenings 33 a and 33 b may be formed by photolithography and etching.

Referring to FIG. 24, a first contact layer 35 a and an intermediateconnection layer 35 b are formed on the lower insulation layer 33. Thefirst contact layer 35 a and the intermediate connection layer 35 b maybe simultaneously formed using the same materials by, for example,lift-off process. For example, the first contact layer 35 a and theintermediate connection layer 35 b may include Al/Ti/Pt/Au/Ti/Ni/Au/Ti.

The first contact layer 35 a has an exterior contact portion 35 c 1 thatcontacts a portion of the first conductive type semiconductor layer 23exposed around the mesa M, and interior contact portions 35 c 2 thatcontact a portion of the first conductive type semiconductor layer 23exposed through the openings 33 a of the lower insulation layer 33. Theexterior contact portion 35 c 1 may have a ring shape surrounding themesa M.

The intermediate connection layer 35 b is electrically insulated fromthe first contact layer 35 a. Referring back to FIGS. 18 and 19, theintermediate connection layer 35 b may be disposed between the openingsof the first contact layer 35 a to be surrounded by the first contactlayer 35 a. The intermediate connection layer 35 b is connected to thesecond contact layer 31 through the openings 33 b of the lowerinsulation layer 33. The intermediate connection layer 35 b may have afinger shape. Although the intermediate connection layer 35 b isdescribed as being formed together with the first contact layer 35 a,the intermediate connection layer 35 b may be alternatively omitted.

Referring to FIG. 25, an upper insulation layer 37 is formed on thefirst contact layer 35 a and the intermediate connection layer 35 b. Theupper insulation layer 37 has openings 37 a that expose the firstcontact layer 35 a, and openings 37 b that expose the intermediateconnection layer 35 b. The openings 37 a may be formed to overlap thefirst contact layer 35 a. The openings 37 b may be formed on theintermediate connection layer 35 b to overlap the second contact layer31. The openings 37 a and 37 b may be formed by patterning theinsulation layer 37 through photolithography and etching. Moreparticularly, the uppermost layers of the first contact layer 35 a andthe intermediate connection layer 35 b, that is, Ti layers, may beremoved during formation of the openings 37 a and 37 b. Although theopenings 37 a and 37 b are described as being separated from each other,the openings 37 a or 37 b may be alternatively connected to each otherto form a single opening.

The openings 37 b may be disposed to overlap the second contact layer 31and have a smaller size intermediate connection layer 35 b. Accordingly,an edge and sidewalk of the intermediate connection layer 35 b arecovered by the upper insulation layer 37. Furthermore, sidewalls of theopenings of the first contact layer 35 a are also covered by the upperinsulation layer 37. The upper insulation layer 37 may have a singlelayer of silicon nitride or silicon oxide, multiple layers thereof, or adistributed Bragg reflector structure.

Referring back to FIG. 17, a first electrode pad 39 a and a secondelectrode pad 39 b are formed on the upper insulation layer 37. Thefirst electrode pad 39 a is connected to the first contact layer 35 athrough the openings 37 a of the upper insulation layer 37, and thesecond electrode pad 39 b is connected to the intermediate connectionlayer 35 b through the openings 37 b of the upper insulation layer 37.The first electrode pad 39 a and the second electrode pad 39 b are usedto mount the light emitting device 10 on a submount or a printed circuitboard. The first electrode pad 39 a and the second electrode pad 39 bmay include Cu.

In the exemplary embodiment, the second electrode pad 39 b and theintermediate connection layer 35 b have a similar shape. Moreparticularly, the second electrode pad 39 b may include fingers and bedisposed on the intermediate connection layer 35 b. In the exemplaryembodiment, the second electrode pad 39 b may have a smaller area thanthe intermediate connection layer 35 b, and is substantially disposed onthe intermediate connection layer 35 b. Then, the substrate 21 isdivided into individual light emitting devices, thereby providingindividually divided light emitting devices, as shown in FIG. 17 to FIG.20.

FIG. 26 is a schematic plan view of the exterior contact portion 35 c 1and interior contact portions 35 c 2 of the light emitting device,according to an exemplary embodiment of the invention.

Referring to FIG. 26, in the light emitting device according to theexemplary embodiment, the exterior contact portion 35 c 1 surrounds themesa M in a ring shape. The exterior contact portion 35 c 1 is separatedfrom the mesa M by the lower insulation layer 33. The interior contactportions 35 c 2 contact the first conductive type semiconductor layer 23exposed through the openings 33 a of the lower insulation layer 33within the through-holes 30 a.

FIG. 27 is a schematic plan view of an exterior contact portion of thelight emitting device, according to an exemplary embodiment of theinvention.

Referring to FIG. 27, exterior contact portions 135 c 1 are formed neareach of side surfaces of the mesa M. Here, the exterior contact portions135 c 1 are separated from each other near corners of the mesa M. Forexample, the lower insulation layer 33 may remain on the firstconductive type semiconductor layer 23 near the corners of the mesa M toprevent the first contact layer 35 a from contacting the firstconductive type semiconductor layer 23. The first contact layer 35 a maybe removed from regions near the corners of the mesa M.

In the exemplary embodiment, since the exterior contact portions 135 c 1are separated from each other near the corners of the mesa M, currentcrowding near the corners of the mesa M may be prevented.

FIG. 28 is a schematic plan view of an interior contact portions of thelight emitting device, according to an exemplary embodiment of theinvention.

Referring to FIG. 28, the interior contact portions include elongatedinterior contact portions 35 c 3. The interior contact portions mayinclude the interior contact portions 35 c 2 described above. A firstelectrode pad 139 a may be disposed on a portion of the interior contactportions 35 c 2 and the interior contact portions 35 c 3.

To form the interior contact portions 35 c 3, through-holes 130 a areformed in the mesa M, and openings 133 a of the lower insulation layer33 are formed in the through-holes 130 a. The through-holes 130 a andthe openings 133 a have an elongated shape. With the elongated interiorcontact portions 35 c 3, the light emitting device may have moreefficient current spreading in the first conductive type semiconductorlayer 23.

FIG. 29 is a schematic plan view of a first electrode pad of the lightemitting device, according to an exemplary embodiment of the invention.

Referring to FIG. 29, a first electrode pad 239 a includes fingers. Thefingers of the first electrode pad 239 a and the fingers of the secondelectrode pad 39 b may be opposed to face each other or alternatelydisposed. In this manner, the fingers may have a greater length.

FIG. 30 is a schematic sectional view of a light emitting deviceincluding a wavelength conversion layer.

Referring to FIG. 30, a wavelength conversion layer 20 is formed on aside of the substrate 21 of the light emitting device 10. The wavelengthconversion layer 20 covers a lower surface of the substrate 21.Furthermore, the wavelength conversion layer 20 may cover a side surfaceof the substrate 21 and a side surface of the first conductive typesemiconductor layer 23. The wavelength conversion layer 20 may alsocover a portion of the upper insulation layer 37.

The wavelength conversion layer 20 of the light emitting device 10 mayconvert wavelengths of light generated in the active layer 25. In thismanner, the light emitting device 10 may realize mixed light, forexample, white light, of wavelength-converted light, and light generatedin the active layer 25.

FIG. 31 is a schematic sectional view of a light emitting module,according to an exemplary embodiment of the invention. FIG. 32A and FIG.32B are respectively a schematic plan view and a schematic rear view ofa submount substrate of the light emitting module according to anexemplary embodiment of the invention, respectively.

Referring to FIG. 31, a light emitting module includes a printed board(PCB) 61, a submount 51, and a light emitting device 10. As describedwith reference to FIG. 30, the light emitting device 10 may include thewavelength conversion layer 20. The submount 51 may be omitted.

The printed circuit board 61 may be a metal PCB, such as an Al-PCB or aCu-PCB, or a ceramic PCB. Since Cu has higher thermal conductivity thanAl, the Cu-PCB may more rapidly dissipate heat from the light emittingdevice 10.

Referring to FIG. 31, FIG. 32A, and FIG. 32B, the submount 51 includesan upper electrode pattern and a lower electrode pattern formed on abase substrate. The upper electrode pattern includes a first upperelectrode 53 a and a second upper electrode 53 b, and the lowerelectrode pattern includes a first lower electrode 55 a and a secondlower electrode 55 b, and may further include a heat dissipation pad 55c.

The base substrate of the submount 51 may be an AIN substrate. Each ofthe upper and lower electrode patterns may have a multilayer structure,in which Ni/Cu/Au layers are stacked. The Ni layer is used to improvebonding strength of electrode patterns to the AlN, and the Au layer isused to prevent oxidation of the Cu layer while improving bondingstrength of the light emitting device 10 to the electrode pads 39 a and39 b. The Cu layer is used for current and heat transfer, and is thickerthan the Ni layer and the Au layer.

Vias 54 a and 54 b are formed through the AlN substrate 51, such thatthe first and second upper electrodes 53 a and 53 b are connected to thefirst and second lower electrodes 55 a and 55 b through the vias 54 aand 54 b.

The heat dissipation pad 55 c is disposed between the first and secondlower electrodes 55 a and 55 b, and is electrically insulated from thefirst and second lower electrodes 55 a and 55 b. The heat dissipationpad 55 c contacts the printed circuit board 61, particularly, a metal ofthe metal PCB 61 to assist in dissipation of heat.

The light emitting device 10 is the same as the light emitting devicedescribed with reference to FIG. 17, and a detailed description of thelight emitting device 10 is not necessary. The light emitting device 10may be turned upside down to have a flip-chip shape, and then mounted onthe submount 51. The electrode pads 39 a and 39 b (see FIG. 17) of thelight emitting device 10 may be bonded to the first and second upperelectrodes 53 a and 53 b of the submount 51.

With submount 51 and the metal PCB 61, the light emitting module mayeasily dissipate heat from the light emitting device 10, thereby furtherimproving current density for operation of the light emitting device 10.

FIG. 33 is an exploded perspective view of an exemplary lightingapparatus to which a light emitting device according to exemplaryembodiments of the invention is applied.

Referring to FIG. 33, the lighting apparatus according to the exemplaryembodiment includes a diffusive cover 1010, a light emitting diodemodule 1020, and a body 1030. The body 1030 may receive the lightemitting diode module 1020, and the diffusive cover 1010 may be disposedin the body 1030 to cover an upper side of the light emitting diodemodule 1020.

The body 1030 may have any shape, so long as the body 1030 may supplyelectric power to the light emitting diode module 1020 and receive andsupport the light emitting diode module 1020. The body 1030 may includea body case 1031, a power supply 1033, a power supply case 1035, and apower source connection section 1037.

The power supply 1033 is received in the power supply case 1035 to beelectrically connected to the light emitting diode module 1020, and mayinclude at least one IC chip (not shown). The IC chip may regulate,change, or control electric power supplied to the light emitting diodemodule 1020. The power supply case 1035 may receive and support thepower supply 1033. The power supply case 1035 having the power supply1033 secured therein may be disposed within the body case 1031. Thepower source connection section 1037 is disposed at a lower end of thepower supply case 1035 and coupled thereto. Accordingly, the powersource connection section 1037 is electrically connected to the powersupply 1033 within the power supply case 1035, and may serve as apassage through which power may be supplied from an external powersource to the power supply 1033.

The light emitting diode module 1020 includes a substrate 1023 and alight emitting diode 1021 disposed on the substrate 1023. The lightemitting diode module 1020 may be disposed at an upper portion of thebody case 1031 and electrically connected to the power supply 1033.

As the substrate 1023, any substrate capable of supporting the lightemitting diode 1021 may be utilized. For example, the substrate 1023 mayinclude a printed circuit board having interconnects formed thereon. Thesubstrate 1023 may have a shape corresponding to a securing portionformed at the upper portion of the body case 1031, so as to be stablysecured to the body case 1031. The light emitting diode 1021 may includeat least one of the light emitting diodes and the light emitting devicesaccording to the exemplary embodiments of the invention described above.

The diffusive cover 1010 is disposed on the light emitting diode 1021and may be secured to the body case 1031 to cover the light emittingdiode 1021. The diffusive cover 1010 may be formed of or include alight-transmitting material, and light orientation of the lightingapparatus may be adjusted through regulation of the shaped opticaltransmissivity of the diffusive cover 1010. As such, the diffusive cover1010 may be modified in various shapes depending on usage andapplications of the lighting apparatus.

FIG. 34 is a sectional view of an exemplary display device to which alight emitting device according to exemplary embodiments of theinvention is applied.

The display device according to the exemplary embodiment includes adisplay panel 2110, a backlight unit supplying light to the displaypanel 2110, and a panel guide supporting a lower edge of the displaypanel 2110.

The display panel 2110 may be, for example, a liquid crystal panelincluding a liquid crystal layer. Gate driving PCBs may be furtherdisposed at the edge of the display panel 2110 to supply driving signalsto a gate line. Here, the gate driving PCBs may be formed on a thin filmtransistor substrate instead of being formed on separate PCBs.

The backlight unit includes a light source module, which includes atleast one substrate and a plurality of light emitting diodes 2160. Thebacklight unit may further include a bottom cover 2180, a reflectivesheet 2170, a diffusive plate 2131, and optical sheets 2130,

The bottom cover 2180 may be open at an upper side thereof to receivethe substrate, the light emitting diodes 2160, the reflective sheet2170, the diffusive plate 2131, and the optical sheets 2130. Inaddition, the bottom cover 2180 may be coupled to the panel guide. Thesubstrate may be disposed under the reflective sheet 2170 to besurrounded by the reflective sheet 2170. However, it should beunderstood that other implementations are also possible. When areflective material is coated onto a surface thereof, the substrate mayalternatively be disposed on the reflective sheet 2170. In this manner,a plurality of substrates may be arranged parallel to one other.Alternatively, the light source module may include a single substrate

The light emitting diodes 2160 may include at least one of the lightemitting diodes and the light emitting devices according to theexemplary embodiments of the invention described above. The lightemitting diodes 2160 may be regularly arranged in a predeterminedpattern on the substrate. In addition, a lens 2210 is disposed on eachof the light emitting diodes 2160 to improve uniformity of light emittedfrom the plurality of light emitting diodes 2160.

The diffusive plate 2131 and the optical sheets 2130 are disposed on thelight emitting devices. Light emitted from the light emitting diodes2160 may be supplied in the form of sheet light to the display panel2110 through the diffusive plate 2131 and the optical sheets 2130. Inthis manner, the light emitting diodes 2160 according to the exemplaryembodiments of the invention may be applied to direct type displays.

FIG. 35 is a sectional view of an exemplary display device to which alight emitting device according to exemplary embodiments of theinvention is applied.

The display device according to the embodiment includes a display panel3210 on which an image is displayed, and a backlight unit disposed at arear side of the display panel 3210 and emitting light thereto. Further,the display device includes a frame supporting the display panel 3210and receiving the backlight unit, and covers 3240 and 3280 surroundingthe display panel 3210.

The display panel 3210 may include, for example, a liquid crystal panelincluding a liquid crystal layer. A gate driving PCB may be furtherdisposed at an edge of the display panel 3210 to supply driving signalsto a gate line. Here, the gate driving PCB may be formed on a thin filmtransistor substrate instead of being formed on a separate PCB. Thedisplay panel 3210 is secured by the covers 3240 and 3280 disposed atupper and lower sides thereof, and the cover 3280 disposed at the lowerside of the display panel 3210 may be coupled to the backlight unit.

The backlight unit supplying light to the display panel 3210 includes alower cover 3270 partially open at an upper side thereof, a light sourcemodule disposed at one side inside the lower cover 3270, and a lightguide plate 3250 disposed parallel to the light source module andconverting spot light into sheet light. In addition, the backlight unitaccording to the exemplary embodiment may further include optical sheets3230 disposed on the light guide plate 3250 to spread and collect light,and a reflective sheet 3260 disposed at a lower side of the light guideplate 3250 and reflecting light traveling in a downward direction of thelight guide plate 3250 towards the display panel 3210.

The light source module includes a substrate 3220 and a plurality oflight emitting diodes 3110 arranged at constant intervals on one surfaceof the substrate 3220. As the substrate 3220, any substrate capable ofsupporting the light emitting diodes 3110 and being electricallyconnected thereto may be utilized. For example, the substrate 3220 mayinclude a printed circuit board.

The light emitting diodes 3110 may include at least one of the lightemitting diodes and the light emitting devices according to theexemplary embodiments of the invention described above. Light emittedfrom the light source module enters the light guide plate 3250 and issupplied to the display panel 3210 through the optical sheets 3230. Thelight guide plate 3250 and the optical sheets 3230 convert spot lightemitted from the light emitting diodes 3110 into sheet light. In thismanner, the light emitting diodes 3110 according to the exemplaryembodiment may be applied to edge type displays.

FIG. 36 is a sectional view of an exemplary headlight to which a lightemitting device according to exemplary embodiments of the invention isapplied.

Referring to FIG. 36, the headlight includes a lamp body 4070, asubstrate 4020, a light emitting diode 4010, and a cover lens 4050. Theheadlight may further include a heat dissipation unit 4030, a supportrack 4060, and a connection member 4040.

The substrate 4020 is secured by the support rack 4060 and disposedabove the lamp body 4070. As the substrate 4020, any member capable ofsupporting the light emitting diode 4010 may be utilized. For example,the substrate 4020 may include a conductive pattern, such as a printedcircuit board. The light emitting diode 4010 is disposed on thesubstrate 4020 and may be supported and secured by the substrate 4020.In addition, the light emitting diode 4010 may be electrically connectedto an external power source through the conductive pattern of thesubstrate 4020. Further, the light emitting diode 4010 may include atleast one of the light emitting diodes and the light emitting devicesaccording to the exemplary embodiments of the invention described above.

The cover lens 4050 is disposed on a path of light emitted from thelight emitting diode 4010. For example, the cover lens 4050 may bespaced apart from the light emitting diode 4010 by the connection member4040, and may be disposed in a direction of supplying light emitted fromthe light emitting diode 4010. By the cover lens 4050, an orientationangle and/or a color of light emitted by the headlight may be adjusted.The connection member 4040 is disposed to secure the cover lens 4050 tothe substrate 4020 while surrounding the light emitting diode 4010, andthus, may function as a light guide that provides a luminous path 4045.The connection member 4040 may include a light reflective material orcoated therewith. The heat dissipation unit 4030 may include heatdissipation fins 4031 and/or a heat dissipation fan 4033, and dissipatesheat generated upon operation of the light emitting diode 4010. In thismanner, the light emitting diodes 4010 according tri the exemplary maybe applied to headlights, particularly, headlights for vehicles.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concept is not limitedto such exemplary embodiments, but rather only by the scope of theappended claims and various modifications and equivalent arrangementsapparent to the skilled artisan.

1.-23. (canceled)
 24. A light emitting device, comprising: a lightemitting structure including a first conductivity type semiconductorlayer and a mesa structure that is formed over the first conductivitytype semiconductor layer to include an active layer and a secondconductivity type semiconductor layer disposed over the active layer,wherein the active layer is structured to emit light in response to anelectrical current through the first and second conductivity typesemiconductor layers; a first electrode connected to the firstconductivity type semiconductor layer and electrically coupled to thefirst conductivity type semiconductor layer via an interior contactregion; a second electrode connected to the second conductivity typesemiconductor layer and electrically coupled to the second conductivitytype semiconductor layer via a second connection region; a firstelectrically conductive pad electrically coupled to the first electrode;a second electrically conductive pad electrically coupled to the secondelectrode; a first insulation layer disposed between the firstelectrically conductive pad and the light emitting structure; and asecond insulation layer disposed between the second electricallyconductive pad and the second electrode and between the first insulationlayer and the first electrically conductive pad, and wherein the mesastructure includes an outer side surface facing externally of the lightemitting device, the first insulation layer covers at least part of theouter side surface of the mesa structure so that the first electrodeincludes a portion located to cover the outer side surface of the mesastructure, and the portion of the first electrode is extended to contactwith the first conductivity type semiconductor layer in an exteriorcontact region that is located externally of the outer side surface ofthe mesa structure.
 25. The light emitting device of claim 24, whereinthe interior contact region is located internally of the outer sidesurface of the mesa structure.
 26. The light emitting device of claim24, wherein the mesa structure is shaped to have portions protrudingfrom the first conductivity type semiconductor layer and separated bythe interior contact region.
 27. The light emitting device of claim 26,wherein the outer side surface of the mesa structure is a side surfaceof one of the portions of the mesa structure that is located closer tothe exterior contact region than remaining portions are.
 28. The lightemitting device of claim 26, wherein at least one of the portions of themesa structure has side surfaces located internally of the outer sidesurface of the mesa structure.
 29. The light emitting device of claim24, wherein the first electrode is formed on a side of the portion ofthe first electrode in the exterior contact region.
 30. The lightemitting device of claim 24, wherein the second insulation layer isformed on a side of the portion of the first electrode in the exteriorcontact region.
 31. The light emitting device of claim 24, wherein themesa structure has an edge disposed within the first conductivity typesemiconductor layer and has a rounded corner.
 32. The light emittingdevice of claim 24, wherein the second insulation layer coverssubstantially whole surface of the first insulation layer.
 33. The lightemitting device of claim 24, wherein at least one of the firstinsulation layer and the second insulation layer comprises SiO₂, TiO₂,or Nb₂O₅.
 34. The light emitting device of claim 24, wherein at leastone of the first insulation layer and the second insulation layerincludes insulating materials that are alternatively stacked one aboveanother.
 35. The light emitting device of claim 24, wherein the secondelectrode comprising Indium tin oxide (ITO) or Zinc Oxide (ZnO).
 36. Thelight emitting device of claim 24, wherein the mesa structure has aninner side surface located further away from an edge of the lightemitting device than the outer side surface of the mesa structure andthe first insulation layer covers at least part of the inner sidesurface of the mesa structure.
 37. The light emitting device of claim24, wherein the mesa structure has an inner side surface located furtheraway from an edge of the light emitting device than the outer sidesurface and the first electrode has a portion located to cover the innerside surface of the mesa structure and extends to be coupled to thefirst conductivity type semiconductor layer in an interior contactregion that is located internally of the outer side surface of the mesastructure.
 38. The light emitting device of claim 24, wherein the firstinsulation layer is shaped to expose the first conductivity typesemiconductor layer through first openings formed in the firstinsulation layer, some of the first openings arranged along a firstdirection from the first electrically conductive pad to the secondelectrically conductive pad.
 39. The light emitting device of claim 38,wherein the first electrode contacts with the first conductivity typesemiconductor layer through the first openings.
 40. The light emittingdevice of claim 38, wherein the first insulation layer is shaped toexpose the second electrode through second openings formed in the firstinsulation layer and arranged along a second direction perpendicular tothe first direction.
 41. The light emitting device of claim 38, whereinthe second insulation layer is shaped to expose the first electrodethrough third openings formed in the second insulation layer andarranged along a second direction perpendicular to the first direction.42. The light emitting device of claim 38, wherein the second insulationlayer has fourth openings to electrically connect the secondelectrically conductive pad to the second electrode, the fourth openingsarranged along a second direction perpendicular to the first direction.43. The light emitting device of claim 24, wherein the first insulationlayer is shaped to expose the first conductivity type semiconductorlayer through a first opening and a second opening that are formed inthe first insulation layer, the first opening located closer to an edgeof the first conductivity type semiconductor layer than the secondopening is and the second opening having an elongated shape extendinginwardly from the edge of the first conductivity type semiconductorlayer.
 44. The light emitting device of claim 43, wherein the firstelectrode contacts with the first conductivity type semiconductor layerthrough the first opening and the second opening.
 45. The light emittingdevice of claim 24, further comprising an intermediate connection layerelectrically insulated from the first semiconductor layer and the firstelectrically conductive pad and electrically coupled to the secondconductivity type semiconductor layer and the second electricallyconductive pad.
 46. The light emitting device of claim 45, wherein theintermediate connection layer includes a surface that is at a sameheight as a surface of a section of the first electrode.
 47. The lightemitting device of claim 45, wherein the first insulation layer and thesecond insulation layer have openings in the first insulation layer andthe second insulation layer, respectively, the openings of the firstinsulation layer and the second insulation layer located under thesecond electrically conductive pad and configured to provide anelectrical contact between the second electrically conductive pad andthe second conductivity type semiconductor layer through theintermediate connection layer.
 48. The light emitting device of claim24, further comprising: a first substrate having a first patternedsurface over which the light emitting structure, the first and secondelectrodes, the first and second electrically conductive pads, and thefirst and second insulation layers are formed; a second substrate thatincludes circuity for supplying the electrical current to the lightemitting structure; and solder contacts formed between the first andsecond electrically conductive pads on the first substrate and thecircuitry on the second substrate to provide electrical connections forthe electrical current to flow from the circuitry on the secondsubstrate to the light emitting structure on the first substrate. 49.The light emitting device of claim 48, wherein: each of the firstelectrically conductive pad and the second electrically conductive padis structured to include electrically conductive pad regions in contactwith the solder contact, and the electrically conductive pad regions arearranged to include gaps between parts of the conductive pad regions.50. The light emitting device of claim 48, further comprising awavelength conversion layer disposed on a second surface of the firstsubstrate that is opposite to the first surface, the wavelengthconversion layer structured to receive light emitted from the lightemitting structure to change a wavelength of the received light.
 51. Thelight emitting device of claim 50, wherein the wavelength conversionlayer extends to cover a side surface of the first substrate and a sidesurface of the first conductivity type semiconductor layer.
 52. A lightemitting device comprising: a light emitting structure including a firstconductivity type semiconductor layer and a mesa structure located overthe first conductivity type layer and including an active layer and asecond conductivity type layer disposed over the active layer, whereinthe active layer is structured to emit light in response to anelectrical current through the first and second conductivity typesemiconductor layers and the mesa structure is surrounded by a mesa edgedisposed internally of the first conductivity type semiconductor layer;a second electrode formed over the mesa structure and electricallycoupled to the second conductivity type semiconductor layer; a firstinsulation layer formed over the mesa structure and the second electrodeand shaped to have first openings exposing the first conductivity typesemiconductor layer and second openings exposing the second electrode; afirst electrode formed over the first insulation layer and electricallycoupled to the first conductivity type semiconductor layer through thefirst openings; a second insulation layer formed over the secondelectrode; a first electrically conductive pad formed over the secondinsulation layer and electrically coupled to the first conductivity typesemiconductor layer through the first openings; a second electricallyconductive pad formed over the second insulation layer and electricallycoupled to the second conductivity type semiconductor layer through thesecond openings, and wherein the first insulation layer, the firstelectrode, and the second insulation layer are arranged on a surface ofthe first conductivity type semiconductor layer between the mesa edgeand an edge of the light emitting device.
 53. The light emitting deviceof claim 52, wherein the surface of the first conductivity typesemiconductor layer provides an exterior contact region locatedexternally of the mesa structure.
 54. The light emitting device of claim53, wherein the exterior contact region has a ring shape surrounding themesa structure.
 55. The light emitting device of claim 53, wherein themesa structure has four side surfaces and the exterior contact region isformed to surround the four side surfaces of the mesa structure exceptcorners of the mesa structure.
 56. The light emitting device of claim52, wherein the mesa structure has an outer side surface facingexternally of the light emitting device, and the first insulation layercovers the outer side surface of the mesa structure.
 57. The lightemitting device of claim 56, wherein the second insulation layer and thesecond electrode are located to cover the outer side surface of the mesastructure.
 58. The light emitting device of claim 52, wherein the mesastructure is shaped to have portions protruding from the firstconductivity type semiconductor layer, the portions spaced apart fromeach other by interior contact regions and the first openings locatedwithin the interior contact regions.
 59. The light emitting device ofclaim 52, wherein the first insulation layer, the first electrode, andthe second insulation layer are arranged in order on the surface of thefirst conductivity type semiconductor layer from the mesa edge toward anedge of the light emitting device.
 60. The light emitting device ofclaim 52, wherein some of the first openings are arranged along a firstdirection from the first electrically conductive pad to the secondelectrically conductive pad and the second openings are arranged along asecond direction perpendicular to the first direction.
 61. The lightemitting device of claim 60, wherein the second insulation layer isshaped to expose the first electrode through third openings formed inthe second insulation layer and arranged along the second direction. 62.The light emitting device of claim 60, wherein the second insulationlayer has fourth openings to electrically connect the secondelectrically conductive pad to the second electrode, the fourth openingsarranged along the second direction.
 63. The light emitting device ofclaim 52, wherein the first openings include elongated openingsextending from a position under the first electrically conductive pad toanother position not under the first electrically conductive pad. 64.The light emitting device of claim 52, wherein the first electrodecontacts with the first conductivity type semiconductor layer throughthe first openings.
 65. The light emitting device of claim 52, furthercomprising an intermediate connection layer electrically insulated fromthe first conductivity type semiconductor layer and the firstelectrically conductive pad and electrically coupled to the secondconductivity type semiconductor layer and the second electricallyconductive pad.
 66. The light emitting device of claim 65, wherein theintermediate connection layer includes a surface that is at a sameheight as a surface of a section of the first electrode.
 67. The lightemitting device of claim 65, wherein the second insulation layer has anopening located under the second electrically conductive pad andconfigured to provide an electrical contact between the secondelectrically conductive pad and the second conductivity typesemiconductor layer through the intermediate connection layer.
 68. Thelight emitting device of claim 65, wherein the second insulation layercovers sidewalls of the intermediate connection layer.
 69. The lightemitting device of claim 52, further comprising: a first substratehaving a first patterned surface over which the light emitting structureis formed and a second opposite surface to the first surface; a secondsubstrate that includes circuitry for supplying the electrical currentto the light emitting structure; and solder contacts formed between thefirst and second electrically conductive pads on the first substrate andthe circuitry on the second substrate to provide electrical connectionsfor the electrical current to flow from the circuitry on the secondsubstrate to the light emitting structure on the first substrate. 70.The light emitting device of claim 69, further comprising a wavelengthconversion layer disposed on the second surface of the first substrateto receive light emitted from the light emitting structure to change awavelength of the received light.
 71. The light emitting device of claim70, wherein the wavelength conversion layer extends to cover a sidesurface of the first substrate and a side surface of the firstconductivity type semiconductor layer.
 72. A light apparatus,comprising; a substrate; a light emitting module disposed on thesubstrate; a cover located to cover the light emitting module; and apower supply connected to the light emitting module through a powersupply connection to regulate, change or control electric power suppliedto the light emitting module, wherein the light emitting module includesa light emitting device as in claim
 24. 73. The light apparatus of claim72, wherein the cover includes a material that transmits light emittedby the light emitting structure.
 74. A light apparatus, comprising; asubstrate; a light emitting module disposed on the substrate; a coverlens located apart from the light emitting module and configured toreceive light emitted from the light emitting module and adjust anoptical property of the received light; a connection member locatedbetween the light emitting module and the cover lens and configured toconnect the cover lens to the substrate; and a heat dissipation unitlocated relative to the light emitting module and configured todissipate heat generated during an operation of the light emittingmodule, and wherein the light emitting module includes a light emittingdevice as in claim
 24. 75. The light apparatus of claim 74, wherein theconnection member includes a light reflective material.
 76. A displaydevice, comprising; a display panel; a backlight unit disposed on a sideof the display panel and configured to supply light to the displaypanel; wherein the backlight unit comprising a substrate and a lightemitting module, wherein the light emitting module includes a lightemitting device as in claim
 24. 77. The display device of claim 76,further comprising a light guide plate located to guide light emittedfrom the backlight unit and a control board connected to the displaypanel and configured to supply a signal to the display panel.
 78. Thedisplay device of claim 76, further comprising: a cover having anopening to receive the substrate; a reflective sheet formed around thesubstrate; a diffusive plate formed over the light emitting module andconfigured to receive light emitted from the light emitting module; andan optical sheet formed over the light emitting module and configured tochange optical properties of the light emitted from the light emittingmodule together.